1. Field of the Invention
The present invention relates to directional solidification apparatus and, more particularly, to high rate directional solidification apparatus employing a liquid cooling bath.
2. Description of the Prior Art
U.S. Pat. No. 3,763,926, of common assignee herewith, discloses an apparatus and process for casting directionally solidified articles at high rates. In the process, a mold resting on a chill plate is heated to an elevated temperature in the heating zone of a furnace, molten metal is then introduced into the heated mold and the mold is gradually withdrawn from the heating zone into a liquid cooling bath, such as molten tin at 500.degree. F. Heat removal through both the chill plate and mold walls establishes a steep thermal gradient in the molten metal and results in unidirectional solidification. Although the apparatus and process of the subject patent have proved highly successful, improvements allowing higher thermal gradients to be achieved in the mold, shorter casting cycles and improved cast microstructures are nevertheless deemed very desirable.